package com.hmdp.service.impl;

import com.baomidou.mybatisplus.core.toolkit.Wrappers;
import com.hmdp.dto.Result;
import com.hmdp.entity.SeckillVoucher;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.SeckillVoucherMapper;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import java.time.LocalDateTime;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import static com.hmdp.utils.RedisConstants.LOCK_ORDER_KEY;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
@RequiredArgsConstructor
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    private final ISeckillVoucherService seckillVoucherService;

    private final RedisIdWorker redisIdWorker;

    private final RedissonClient redissonClient;

    private final StringRedisTemplate stringRedisTemplate;

    private  IVoucherOrderService proxy;

    // 初始化lua脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    //异步处理线程池
    private final static ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    // 阻塞队列
    private BlockingQueue<VoucherOrder> orderTasks =new ArrayBlockingQueue<>(1024 * 1024);
    //在类初始化之后执行，因为当这个类初始化好了之后，随时都是有可能要执行的
    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    @Override
    public Result seckillVoucher(Long voucherId) {
        /*//1.查询优惠券
        SeckillVoucher seckillVoucher = seckillVoucherService.getById(voucherId);
        // 2.判断秒杀是否开始
        if (seckillVoucher.getBeginTime().isAfter(LocalDateTime.now())){
            // 尚未开始
            return Result.fail("秒杀尚未开始");
        }
        // 3.判断秒杀是否已经结束
        if (seckillVoucher.getEndTime().isBefore(LocalDateTime.now())){
            // 已经结束
            return Result.fail("秒杀已经结束");
        }
        // 4.判断库存是否充足
        if (seckillVoucher.getStock() < 1){
            // 库存不足
            return Result.fail("库存不足");
        }*/
        //获取用户
        Long userId = UserHolder.getUser().getId();
        // 1.执行lua脚本 使用redis实现判断库存和一人一单
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString()
        );
        int i = result.intValue();
        //2.判断结果是否为0
        if (i != 0){
            //2.1不为0，代表没有购买资格
            return Result.fail(i == 1 ? "库存不足" : "不能重复下单");
        }
        VoucherOrder voucherOrder = new VoucherOrder();
        // 2.3.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 2.4.用户id
        voucherOrder.setUserId(userId);
        // 2.5.代金券id
        voucherOrder.setVoucherId(voucherId);
        //2.6放入阻塞队列中
//        //加锁  intern()方法在同一个线程中，使用同一把锁不会创建新的对象 所以使用intern()方法
//        synchronized (userId.toString().intern()){
//            //获取代理对象（事务）获得原始的事务对象， 来操作事务
//            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
//            proxy.createVoucherOrder(voucherId);
//            return Result.ok(voucherId);
//        }
        //创建锁对象 用redisson分布式锁
        RLock lock = redissonClient.getLock(LOCK_ORDER_KEY + userId);
        boolean isLock = lock.isLocked();
        if (!isLock) {
            return Result.fail("不允许重复下单");
        }
        try {
            //获取代理对象(事务)
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } finally {
            //释放锁
            lock.unlock();
        }
    }

    /**
     * 实现一人一单，秒杀防止超卖
     * @param voucherId
     * @return
     */
    @Transactional
    public Result createVoucherOrder(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        // 5.1.查询订单
        int count = lambdaQuery().eq(VoucherOrder::getUserId, userId).eq(VoucherOrder::getVoucherId, voucherId).count();
//        int count = count(Wrappers.<VoucherOrder>lambdaQuery().eq(VoucherOrder::getUserId, userId).eq(VoucherOrder::getVoucherId, voucherId));
        // 5.2.判断是否存在
        if (count > 0){
            // 用户已经购买过
            return Result.fail("用户已经购买过");
        }
        //6.扣减库存
        boolean success = seckillVoucherService.update(
                Wrappers.<SeckillVoucher>lambdaUpdate()
                        .setSql("stock = stock - 1") // 直接在数据库层面执行自减
                        .eq(SeckillVoucher::getVoucherId, voucherId)
                        .gt(SeckillVoucher::getStock, 0) // 防止超卖 减到0
        );
        if (!success ){
            return Result.fail("库存不足");
        }
        //7.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        // 7.1.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 7.2.用户id
        voucherOrder.setUserId(userId);
        // 7.3.代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        // 8.返回订单id
        return Result.ok(orderId);
    }
    // 用于线程池处理的任务
    // 当初始化完毕后，就会去从对列中去拿信息
    // 线程池处理异步任务 阻塞队列实现
    private class VoucherOrderHandler implements Runnable{
        @Override
        public void run() {
            while (true){
                try {
                    // 1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                }catch (Exception e){
                    log.error("订单处理失败",e);
                }
            }
        }

        private void handleVoucherOrder(VoucherOrder voucherOrder) {
            //1.获取用户id
            Long userId = voucherOrder.getUserId();
            //2.创建锁对象
            RLock lock = redissonClient.getLock(LOCK_ORDER_KEY + userId);
            //3.判断是否获取锁成功
            boolean isLock = lock.tryLock();
            if (!isLock){
                //4.获取锁失败，直接返回失败或者重试
                log.error("不允许重复下单");
                return;
            }
            try {
                //注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
                proxy = (IVoucherOrderService)AopContext.currentProxy();
            }finally {
                //7.释放锁
                lock.unlock();
            }
        }

        public Result seckillVoucher(Long voucherId) {
            Long userId = UserHolder.getUser().getId();
            long orderId = redisIdWorker.nextId("order");
            // 1.执行lua脚本
            Long result = stringRedisTemplate.execute(
                    SECKILL_SCRIPT,
                    Collections.emptyList(),
                    voucherId.toString(), userId.toString(), String.valueOf(orderId)
            );
            int r = result.intValue();
            // 2.判断结果是否为0
            if (r != 0) {
                // 2.1.不为0 ，代表没有购买资格
                return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
            }
            VoucherOrder voucherOrder = new VoucherOrder();
            // 2.3.订单id
            voucherOrder.setId(orderId);
            // 2.4.用户id
            voucherOrder.setUserId(userId);
            // 2.5.代金券id
            voucherOrder.setVoucherId(voucherId);
            // 2.6.放入阻塞队列
            orderTasks.add(voucherOrder);
            //3.获取代理对象
            proxy = (IVoucherOrderService)AopContext.currentProxy();
            //4.返回订单id
            return Result.ok(orderId);
        }

        @Transactional
        public  void createVoucherOrder(VoucherOrder voucherOrder) {
            Long userId = voucherOrder.getUserId();
            // 5.1.查询订单
            int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
            // 5.2.判断是否存在
            if (count > 0) {
                // 用户已经购买过了
                log.error("用户已经购买过了");
                return ;
            }

            // 6.扣减库存
            boolean success = seckillVoucherService.update()
                    .setSql("stock = stock - 1") // set stock = stock - 1
                    .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock", 0) // where id = ? and stock > 0
                    .update();
            if (!success) {
                // 扣减失败
                log.error("库存不足");
                return ;
            }
            save(voucherOrder);
        }
    }
}
